Enhanced energy recovery in municipal wastewater treatment plants through co-digestion by anaerobic membrane bioreactors: current status and future perspectives

Today, the transition to renewable energy from conventional energy practices is more important than ever to establish energy security and mitigate climate change. The wastewater treatment plants (WWTP) consume a remarkable amount of energy and cause significant greenhouse gas emissions. The energy balance of WWTP can be improved by implementing energy-efficient applications such as anaerobic digestion. However, most of the existing WWTPs utilize only sewage sludge in conventional anaerobic digesters (CAD) which results in low biogas generation. Generally, co-digestion is indicated as an effective solution for the low biogas generation faced in mono-digestion. Moreover, recently, anaerobic membrane bioreactors (AnMBR) have been promoted as a prominent alternative to CADs. This paper overviews the current situation of co-digestion applications by AnMBRs for municipal WWTPs. Furthermore, the environmental and economic aspects of these applications were reviewed. Lastly, challenges and future perspectives related to the co-digestion applications by AnMBR were thoroughly discussed.